d0be1e954bd4674fc27f2616c72adb37cf3525a2David Lawrence<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"

70e5a7403f0e0a3bd292b8287c5fed5772c15270Automatic Updater "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"

499b34cea04a46823d003d4c0520c8b03e8513cbBrian Wellington [<!ENTITY mdash "&#8212;">]>

821644d49b73b49f2abc5463bc53a3132f612478Mark Andrews

9c3531d72aeaad6c5f01efe6a1c82023e1379e4dDavid Lawrence<refentry>

0e9dcd548051a8ec34744bfa18b4e09fea742a39Andreas Gustafsson

ee6fe1d1975604af266af6c370fc6193dae80fddMichael Sawyer <refentryinfo>

f333ea9bdd3f85b74ae790e6c8ce2684295b3483Andreas Gustafsson <date>June 18, 2007</date>

533df4efdafcf7a8b7292a298f45df9ab7f7f7f9Mark Andrews </refentryinfo>

10bc8ffed60f064a2950527a82d7fdffe91b6206Michael Sawyer

0e9dcd548051a8ec34744bfa18b4e09fea742a39Andreas Gustafsson <refmeta>

0e9dcd548051a8ec34744bfa18b4e09fea742a39Andreas Gustafsson <refentrytitle>lwres_context</refentrytitle>

5a77e9620a0b2f7417469c98be374de49d0eccc6Andreas Gustafsson <manvolnum>3</manvolnum>

0e9dcd548051a8ec34744bfa18b4e09fea742a39Andreas Gustafsson <refmiscinfo>BIND9</refmiscinfo>

0e9dcd548051a8ec34744bfa18b4e09fea742a39Andreas Gustafsson </refmeta>

0e9dcd548051a8ec34744bfa18b4e09fea742a39Andreas Gustafsson

0e9dcd548051a8ec34744bfa18b4e09fea742a39Andreas Gustafsson <docinfo>

0e9dcd548051a8ec34744bfa18b4e09fea742a39Andreas Gustafsson <copyright>

0e9dcd548051a8ec34744bfa18b4e09fea742a39Andreas Gustafsson <year>2004</year>

0e9dcd548051a8ec34744bfa18b4e09fea742a39Andreas Gustafsson <year>2005</year>

0e9dcd548051a8ec34744bfa18b4e09fea742a39Andreas Gustafsson <year>2007</year>

0e9dcd548051a8ec34744bfa18b4e09fea742a39Andreas Gustafsson <year>2014</year>

a2b565626ba9a98eecc7b82cb86c6d68c38d3d94Michael Sawyer <holder>Internet Systems Consortium, Inc. ("ISC")</holder>

a2b565626ba9a98eecc7b82cb86c6d68c38d3d94Michael Sawyer </copyright>

a2b565626ba9a98eecc7b82cb86c6d68c38d3d94Michael Sawyer <copyright>

a2b565626ba9a98eecc7b82cb86c6d68c38d3d94Michael Sawyer <year>2000</year>

a2b565626ba9a98eecc7b82cb86c6d68c38d3d94Michael Sawyer <year>2001</year>

0e9dcd548051a8ec34744bfa18b4e09fea742a39Andreas Gustafsson <year>2003</year>

<holder>Internet Software Consortium.</holder>

</copyright>

</docinfo>

<refnamediv>

<refname>lwres_context_create</refname>

<refname>lwres_context_destroy</refname>

<refname>lwres_context_nextserial</refname>

<refname>lwres_context_initserial</refname>

<refname>lwres_context_freemem</refname>

<refname>lwres_context_allocmem</refname>

<refname>lwres_context_sendrecv</refname>

<refpurpose>lightweight resolver context management</refpurpose>

</refnamediv>

<refsynopsisdiv>

<funcsynopsis>

<funcsynopsisinfo>#include &lt;lwres/lwres.h&gt;</funcsynopsisinfo>

<funcprototype>

<funcdef>

lwres_result_t

<function>lwres_context_create</function></funcdef>

<paramdef>lwres_context_t **<parameter>contextp</parameter></paramdef>

<paramdef>void *<parameter>arg</parameter></paramdef>

<paramdef>lwres_malloc_t <parameter>malloc_function</parameter></paramdef>

<paramdef>lwres_free_t <parameter>free_function</parameter></paramdef>

</funcprototype>

<funcprototype>

<funcdef>

lwres_result_t

<function>lwres_context_destroy</function></funcdef>

<paramdef>lwres_context_t **<parameter>contextp</parameter></paramdef>

</funcprototype>

<funcprototype>

<funcdef>

void

<function>lwres_context_initserial</function></funcdef>

<paramdef>lwres_context_t *<parameter>ctx</parameter></paramdef>

<paramdef>lwres_uint32_t <parameter>serial</parameter></paramdef>

</funcprototype>

<funcprototype>

<funcdef>

lwres_uint32_t

<function>lwres_context_nextserial</function></funcdef>

<paramdef>lwres_context_t *<parameter>ctx</parameter></paramdef>

</funcprototype>

<funcprototype>

<funcdef>

void

<function>lwres_context_freemem</function></funcdef>

<paramdef>lwres_context_t *<parameter>ctx</parameter></paramdef>

<paramdef>void *<parameter>mem</parameter></paramdef>

<paramdef>size_t <parameter>len</parameter></paramdef>

</funcprototype>

<funcprototype>

<funcdef>

void

<function>lwres_context_allocmem</function></funcdef>

<paramdef>lwres_context_t *<parameter>ctx</parameter></paramdef>

<paramdef>size_t <parameter>len</parameter></paramdef>

</funcprototype>

<funcprototype>

<funcdef>

void *

<function>lwres_context_sendrecv</function></funcdef>

<paramdef>lwres_context_t *<parameter>ctx</parameter></paramdef>

<paramdef>void *<parameter>sendbase</parameter></paramdef>

<paramdef>int <parameter>sendlen</parameter></paramdef>

<paramdef>void *<parameter>recvbase</parameter></paramdef>

<paramdef>int <parameter>recvlen</parameter></paramdef>

<paramdef>int *<parameter>recvd_len</parameter></paramdef>

</funcprototype>

</funcsynopsis>

</refsynopsisdiv>

<refsect1>

<title>DESCRIPTION</title>

<para><function>lwres_context_create()</function>

creates a <type>lwres_context_t</type> structure for use in

lightweight resolver operations. It holds a socket and other

data needed for communicating with a resolver daemon. The new

<type>lwres_context_t</type> is returned through

<parameter>contextp</parameter>, a pointer to a

<type>lwres_context_t</type> pointer. This

<type>lwres_context_t</type> pointer must initially be NULL, and

is modified to point to the newly created

<type>lwres_context_t</type>.

</para>

<para>

When the lightweight resolver needs to perform dynamic memory

allocation, it will call

<parameter>malloc_function</parameter>

to allocate memory and

<parameter>free_function</parameter>

to free it. If

<parameter>malloc_function</parameter>

and

<parameter>free_function</parameter>

are NULL, memory is allocated using

<citerefentry>

<refentrytitle>malloc</refentrytitle><manvolnum>3</manvolnum>

</citerefentry>.

and

<citerefentry>

<refentrytitle>free</refentrytitle><manvolnum>3</manvolnum>

</citerefentry>.

It is not permitted to have a NULL

<parameter>malloc_function</parameter> and a non-NULL

<parameter>free_function</parameter> or vice versa.

<parameter>arg</parameter> is passed as the first parameter to

the memory allocation functions. If

<parameter>malloc_function</parameter> and

<parameter>free_function</parameter> are NULL,

<parameter>arg</parameter> is unused and should be passed as

NULL.

</para>

<para>

Once memory for the structure has been allocated,

it is initialized using

<citerefentry>

<refentrytitle>lwres_conf_init</refentrytitle><manvolnum>3</manvolnum>

</citerefentry>

and returned via <parameter>*contextp</parameter>.

</para>

<para><function>lwres_context_destroy()</function>

destroys a <type>lwres_context_t</type>, closing its socket.

<parameter>contextp</parameter> is a pointer to a pointer to the

context that is to be destroyed. The pointer will be set to

NULL when the context has been destroyed.

</para>

<para>

The context holds a serial number that is used to identify

resolver request packets and associate responses with the

corresponding requests. This serial number is controlled using

<function>lwres_context_initserial()</function> and

<function>lwres_context_nextserial()</function>.

<function>lwres_context_initserial()</function> sets the serial

number for context <parameter>*ctx</parameter> to

<parameter>serial</parameter>.

<function>lwres_context_nextserial()</function> increments the

serial number and returns the previous value.

</para>

<para>

Memory for a lightweight resolver context is allocated and freed

using <function>lwres_context_allocmem()</function> and

<function>lwres_context_freemem()</function>. These use

whatever allocations were defined when the context was created

with <function>lwres_context_create()</function>.

<function>lwres_context_allocmem()</function> allocates

<parameter>len</parameter> bytes of memory and if successful

returns a pointer to the allocated storage.

<function>lwres_context_freemem()</function> frees

<parameter>len</parameter> bytes of space starting at location

<parameter>mem</parameter>.

</para>

<para><function>lwres_context_sendrecv()</function>

performs I/O for the context <parameter>ctx</parameter>. Data

are read and written from the context's socket. It writes data

from <parameter>sendbase</parameter> &mdash; typically a

lightweight resolver query packet &mdash; and waits for a reply

which is copied to the receive buffer at

<parameter>recvbase</parameter>. The number of bytes that were

written to this receive buffer is returned in

<parameter>*recvd_len</parameter>.

</para>

</refsect1>

<refsect1>

<title>RETURN VALUES</title>

<para><function>lwres_context_create()</function>

returns <errorcode>LWRES_R_NOMEMORY</errorcode> if memory for

the <type>struct lwres_context</type> could not be allocated,

<errorcode>LWRES_R_SUCCESS</errorcode> otherwise.

</para>

<para>

Successful calls to the memory allocator

<function>lwres_context_allocmem()</function>

return a pointer to the start of the allocated space.

It returns NULL if memory could not be allocated.

</para>

<para><errorcode>LWRES_R_SUCCESS</errorcode>

is returned when

<function>lwres_context_sendrecv()</function>

completes successfully.

<errorcode>LWRES_R_IOERROR</errorcode>

is returned if an I/O error occurs and

<errorcode>LWRES_R_TIMEOUT</errorcode>

is returned if

<function>lwres_context_sendrecv()</function>

times out waiting for a response.

</para>

</refsect1>

<refsect1>

<title>SEE ALSO</title>

<para><citerefentry>

<refentrytitle>lwres_conf_init</refentrytitle><manvolnum>3</manvolnum>

</citerefentry>,

<citerefentry>

<refentrytitle>malloc</refentrytitle><manvolnum>3</manvolnum>

</citerefentry>,

<citerefentry>

<refentrytitle>free</refentrytitle><manvolnum>3</manvolnum>

</citerefentry>.

</para>

</refsect1>

</refentry><!--